| Variable depth of cut machining (VDCM) refers to machining systems that have the ability to vary the depth of cut rapidly by utilizing fast-tool servos. In recent years, researchers have investigated the development of VDCM for several industrial applications. These include both the turning of non-circular workpieces and the compensation of process-generated dynamic errors. Deficiencies in existing VDCM systems include insufficient speed, accuracy, and servo stiffness. The goal of the proposed research is to advance VDCM to industrial applicability. Specifically, the research objectives are: (1) to develop an industrial grade VDCM system capable of compensating for cylindricity errors in machined bores caused by workpiece flexibility; and (2) to investigate methods to control a VDCM system while operating under programmed variations in the spindle speed.; The contributions of this research include: (1) Design, analysis and control of a fast tool servo capable of operating at industrial cutting conditions. (2) Formulation and experimental demonstration of a process cycle feedback learning control system used for the compensation of cutting force induced cylindricity errors in machined bores. (3) Formulation of analysis and design techniques of repetitive controllers for linear periodic time varying systems. (4) Application of periodic repetitive control to a VDCM system operating under programmed variation of the spindle speed for the purpose of increasing the cutting stability margin. |
